Effects of tillage on macronutrients in soil and wheat of a long-term dryland wheat-pea rotation

Authors: SHIWAKOTIA, SANTOSH - Oregon State University; ZHELJAZKOV, VALTCHO - Oregon State University; Gollany, Hero; XING, BAOSHAN - University Of Massachusetts; KLEBER, MARKUS - Oregon State University

Submitted to: Soil and Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2019
Publication Date: 4/19/2019
Citation: Shiwakotia, S., Zheljazkov, V.D., Gollany, H.T., Xing, B. 2019. Tillage affects macronutrients in soil and wheat of a long-term dryland wheat-pea rotation. Soil and Tillage Research. 190:194-201. https://doi.org/10.1016/j.still.2019.02.004.
DOI: https://doi.org/10.1016/j.still.2019.02.004

Interpretive Summary: Tillage is known to significantly affect crop residue decomposition and soil nutrient dynamics, but their impacts on soil and plant macronutrients content with time have not been reported. This study was conducted to assess tillage timing and intensity influence on soil and wheat macronutrient content of winter wheat-dry pea rotation under a dryland cropping system, and to compare macronutrients in the tillage treatments with a nearby long-term grass pasture. The tillage treatments were fall tillage (FT), spring tillage (ST), no-tillage (NT) and disk/chisel tillage (DT/CT). Soil samples from 1995, 2005, and 2015 were analyzed to determine soil organic carbon, total nitrogen and sulfur, extractable phosphorous, potassium, calcium, and magnesium, and soil acidity (pH). The impact of tillage on soil macronutrients was evident after 52 years of wheat-pea rotation. As a result, greater concentration of soil organic carbon, total sulfur, and extractable phosphorous, and potassium were observed under NT than under FT or ST. The wheat-pea plots lost 28, 46, and 67% of soil organic carbon, magnesium, and sulfur, respectively, in the top 4 inches of soil compared with grass pasture plots, whereas the NT plots were the only plots in WW-P to maintain a phosphorous concentration comparable with grass pasture plots at the same depth. The results indicated that NT could be beneficial to recharge the soil nutrient pool over time compared to FT or ST.

Technical Abstract: Tillage is known to significantly affect crop residue decomposition and soil nutrient dynamics, but their impacts on soil and plant macronutrients concentration with time have not been reported. This study was conducted (1) to assess influence of tillage timing and intensity on soil and wheat (Triticum aestivum L.) macronutrient content of winter wheat-dry pea (Pisum sativum L.) rotation (WW-P) under a dryland cropping system, and (ii) to compare macronutrients in the tillage treatments with a nearby long-term grass pasture (GP). The tillage treatments were fall tillage (FT), spring tillage (ST), no-tillage (NT) and disk/chisel tillage (DT/CT). Soil samples from 1995, 2005, and 2015 were analyzed to determine the concentration of soil organic carbon (SOC), total N and S, Mehlich II extractable P, K, Ca, and Mg, and soil pH. The impact of tillage on soil macronutrients was evident after 52 years of WW-P. As a result, greater concentration of SOC, total S, and extractable P and K were observed under NT than under FT or ST. The WW-P plots lost 28, 46, and 67% of SOC, Mg, and S, respectively, in the top 10 cm of soil compared with GP plots, whereas the NT plots were the only plots in WW-P to maintain a P concentration (99 mg P /kg) comparable with GP plots (102 mg P/kg) at the same depth. The results indicated that NT could be beneficial to recharge the soil nutrient pool over time compared to FT or ST.